A dial tone is the sound of a line that is open but empty, so it is read as readiness to connect with no one yet on the other end. Tradition links it to waiting and to unspoken intentions.
Does the traditional reading fit your dream, or did it mean something else to you?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.